NR3C2 and obesity due to melanocortin 4 receptor deficiency: In order to investigate whether MR blockade was able to influence insulin signaling in SM, preserving insulin sensitivity in this tissue in obesity, we treated mice with insulin or a vehicle for 15 min in experimental mice after 12 weeks on HFD or HFD plus Spiro treatment, and we measured Akt phosphorylation in the GA.